Genetic approaches have provided major insights into the molecular pathogenesis of Alzheimer's disease (AD). However, only about 3% of all of AD is due to genetic mutations in either amyloid precursor protein (APP), or presenilin 1 or 2 (PS1, PS2). We propose to generate a human in vitro model using induced pluripotent stem (iPS) cells, in which the genetic and developmental aspects of familial and sporadic AD can be studied more accurately and therapeutic targets can be identified for subsequent drug discovery. The following Specific Aims are proposed: Specific Aim 1: To generate iPS cells and neurons from skin fibroblasts from subjects with familial and sporadic AD. We have already succeeded in generating differentiated neurons from fibroblasts from subjects with PS1 mutations. We have demonstrated that differentiation of these neurons leads to their acquisition of an obvious standard molecular phenotype; i.e., a shift in the A 42/40 ratio). The initial essential standardization of these neurons will include, for each PS1 mutation, the exploration of intra-individual and inter-individual variability in the A 42/40 phenotype within patients, affectd and unaffected family members, and across different families that carry either the identical mutation or across different PS1 mutations. A longer-term goal will be the generation of glia and mixed cell cultures. Specific Aim 2: To perform molecular, biochemical and functional characterization of AD iPS cell lines. We have defined a culture system for AD iPS cell-derived neurons that includes the essential A 42/40 phenotype. We will now proceed to establish the content of AD-related molecules in these iPS cells while seeking to establish the cell biological basis for the A 42/40 phenotype. This will include an assessment of the autophagic pathway. Specific Aim 3: Identification of transcriptional profiles of familial and sporadic AD iPS cells. Or primary goal in this aim is to establish a baseline molecular characterization of forebrain neural cells derived from the panel of iPS cell lines specified above. Informatic analysis of these profiles will be performed in order to identify possible AD-related networks, as recently defined by Geschwind and colleagues. We will study how in vitro cellular and molecular phenotypes in telencephalic neural cells derived from patient iPS cells vary and are similar across individuals and mutations related to either familial or sporadic AD. PUBLIC HEALTH RELEVANCE: Genetic approaches have provided major insights into the molecular pathogenesis of Alzheimer's disease (AD). However, only about 3% of all of AD is due to genetic mutations in either amyloid precursor protein (APP), or presenilin 1 or 2 (PS1, PS2). We propose to generate a human in vitro model using induced pluripotent stem (iPS) cells, in which the genetic and developmental aspects of familial and sporadic AD can be studied more accurately and therapeutic targets can be identified for subsequent drug discovery.